I have a 1990 f250 5.8 4X4 that I am getting close to being a daily driver, thanks to the help and advice from this forum. The truck runs very well but after being warmed up and driven a few miles it cranks over hard, almost like a near dead battery. (Battery is brand new.) My search on this forum suggests that my ignition timing might be too far advanced. My Chilton manual seems to indicate that I have the TFI-IV ignition, since it doesn't have a vacuum line to the distributor, and Chilton states that "no ignition timing adjustment is possible and none should be attempted". Do I really have a timing issue and if so, how do I fix it? Thank you in advance for any help!!
Yes you do have a TFI ignition system, but...there is a base tiing that must be achieved. Using a timing light, remove the Spout connector and verify @ the timing pointer that the base timing is 10 degrees BTDC. After verifing base timing, plug the Spout connector back in and verify that it advances. Reading your post, I'm more inclined ot think that perhaps the Ignition coil is to blame. Easy check for this is to let the truck sit several hours to cool down, then use a hair dryer or another means of heating the coil up. Once you have got it warm (Not melted), try to start the truck as you have in the past. Is it hard ot start? If so, the coil is most likely on it's way out and it's far better to replace now, rather than in 18 inches of snow like I had mine go out and couldn't get it figured out, except for your idea of a Dead battery.
Also, you TFI module is located on the distributor itself. These are known to fail due to the amout of stress they endure from the vibration, heat and other factors putting them to the extreme due to the location. Ford revised the TFI module to be located on the Driver side Fenderwell with a large aluminium heatsink. Also, try the hairdryer trick with the TFI module "IF" your diagnosis leads you there, ruling out the coil as the culprit.
Thankyou timbersteel!!! I will check intial timing first. Is the spout connecter the plug on the distributor or somewhere else? I wouldn't think it was the distributor plug but I'm fairly new to Fords. Thank you
On the dizzy-mounted TFI, I believe it located close to the distributor, but I haven't a system like yours to take a pic. My '90 rebuild is identical to yours, but the harness isn't with me right now. RLA2005, maybe Subford has a pic of it, (I've seen it here several times, try searching for Spout Connector, Subford) but it is a grey Spout connector and it may be wrapped in black electrical fabric tape or if someone has accessed it, it will or should be Grey in color.
Thanks for the pics RLA! I knew that you and Subford had them and the latter one is of mine. Gonna keep this saved in my fav's and save the picture for future reference with courtesy calls for both of you.